aggre0 bus clks are not associated with any of the drivers, so its
important that these clks are always on to get peripherals on this
bus working. So mark them as critical.

Eventually when we have a proper bus driver these clks can be marked
appropriately.

Without this patch pcie on db820c is not functional.
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>